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Cells: Prokaryote vs Eukaryote What to STUDY????? •Know kingdoms for eukaryotic and prokaryotic cells. •Know 4 similarities and differences – cell wall and size!!! •Know how prokaryotes reproduce •Know pilli and nucleoid •Know 4 ways they obtain food •Know 3 bacteria that are harmful and what they cause •Know why bacteria make you sick •Know 3 ways they are helpful •Know examples of prokaryotes and eukaryotes •Know the 3 shapes of bacteria Prokaryotic Cells Eukaryotic cells small cells (< 5 mm) larger cells (> 10 mm) always unicellular often multicellular no nucleus or any membrane-bound organelles always have nucleus and other membrane-bound organelles DNA is circular, FREE FLOATING DNA DNA is linear and associated with proteins to form chromatin ribosomes are small ribosomes are large Summary of differences! no cytoskeleton PILLI and capsule Cell wall made of peptidoglycan always has a cytoskeleton Cell wall made out of cellulose cell division is by binary fission cell division is by mitosis or meiosis reproduction is always asexual reproduction is asexual or sexual Similarities between Prokaryotic and Eukaryotic Cells *Ribosomes *DNA *Cell membrane *7 characteristics of life – reproduction, cells *Some have cell walls *Some have flagella *Cytoplasm What is a pathogen? Microorganisms that make you sick Why do they make you sick? To get food they need to survive and reproduce How do they make you sick? They produce poisons (toxins) that result in fever, headache, vomiting, and diarrhea and destroy body tissue USDA NIFSI Food Safety in the Classroom© University of Tennessee, Knoxville 2006 Helpful Bacteria •Used to treat sewage Organic waste is consumed by the bacteria, used as nutrients by the bacteria, and is no longer present to produce odors, sludge, pollution, or unsightly mess. •foods like yogurt, cottage & Swiss cheese, sour cream, buttermilk are made from bacteria that grows in milk • Overview: They’re (Almost) Everywhere! • Most prokaryotes are microscopic – But what they lack in size they more than make up for in numbers • The number of prokaryotes in a single handful of fertile soil – Is greater than the number of people who have ever lived • Prokaryotes thrive almost everywhere – Including places too acidic, too salty, too cold, or too hot for most other organisms Figure 27.1 • Prokaryotic cells have a variety of shapes – The three most common of which are spheres (cocci), rods (bacilli), and spirals 1 m (a) Spherical Figure 27.2a–c(cocci) 2 m (b) Rod-shaped (bacilli) 5 m (c) Spiral wall (a) Lipopolysaccharide Peptidoglycan layer Cell wall Outer membrane Peptidoglycan layer Plasma membrane Plasma membrane Protein Protein Grampositive bacteria Gramnegative bacteria 20 m (b) Gram-positive. More peptidoglycan Gram-negative. Less peptiodglycan • Using a technique called the Gram stain – Scientists can classify many bacterial species into two groups based on cell wall composition, Gram-positive and Gram-negative • Some prokaryotes have fimbriae and pili – Which allow them to stick to their substrate or other individuals in a colony Fimbriae 200 nm Figure 27.5 Motility Flagellum Filament 50 nm Cell wall Figure 27.6 Hook Basal apparatus Plasma membrane • Most motile bacteria propel themselves by flagella – Which are structurally and functionally different from eukaryotic flagella Chromosome Figure 27.8 1 m • The typical prokaryotic genome – Is a ring of DNA that is not surrounded by a membrane and that is located in a nucleoid region Reproduction and Adaptation Prokaryotes reproduce quickly by binary fission And can divide every 1–3 hours Endospore Figure 27.9 0.3 m • Many prokaryotes form endospores(this is why they can live anywhere!) – Which can remain viable in harsh conditions for centuries Nitrogen Metabolism • Prokaryotes can metabolize nitrogen – In a variety of ways • In a process called nitrogen fixation – Some prokaryotes convert atmospheric nitrogen to ammonia Chemical Recycling • Prokaryotes play a major role – In the continual recycling of chemical elements between the living and nonliving components of the environment in ecosystems Symbiotic Relationships Figure 27.15 • Many prokaryotes – Live with other organisms in symbiotic relationships such as mutualism and commensalism • Other types of prokaryotes – Live inside hosts as parasites • Concept 27.5: Prokaryotes have both harmful and beneficial impacts on humans • Some prokaryotes are human pathogens – But many others have positive interactions with humans Pathogenic Prokaryotes • Prokaryotes cause about half of all human diseases – Lyme disease is an example Figure 27.16 5 µm • Pathogenic prokaryotes typically cause disease – By releasing exotoxins or endotoxins – Exotoxins – proteins released poisons the cell. – Endotoxins – parts of dead bacteria that poisons the cell • Many pathogenic bacteria – Are potential weapons of bioterrorism Prokaryotes in Research and Technology • Experiments using prokaryotes – Have led to important advances in DNA technology • Prokaryotes are the principal agents in bioremediation – The use of organisms to remove pollutants from the environment Figure 27.17 • Prokaryotes are also major tools in – Mining – The synthesis of vitamins – Production of antibiotics, hormones, and other products Cells have evolved two different architectures: Prokaryote “style” – before nucleus Eukaryote “style” – true nucleus Two Basic Types of Cells _____________________ From the Virtual Microbiology Classroom on ScienceProfOnline.com _____________________ Images: Prokaryotic cell diagram & Eukaryotic cell diagram, M. Ruiz Prokaryotic Kingdoms Archaebacteria Eubacteria Prokaryotic Cells Prokaryotic cells lack a membrane-bound nucleus. -genetic material is present in the nucleoid 36 Prokaryotic Cells Have -genetic material in the nucleoid -cytoplasm -cell membrane -cell wall -ribosomes -no membrane-bound organelles 37 Prokaryotic Cells Prokaryotic cell walls -protect the cell and maintain cell shape -may be composed of peptidoglycan Archaean cell walls lack peptidoglycan. 38 Prokaryotic Cells Flagella -present in some prokaryotic cells -used for locomotion -rotary motion propels the cell 39 Prokaryote cells are smaller and simpler Commonly known as bacteria 10-100 microns in size Single-celled(unicellular) Size of Living Things 1 m = 100 cm = 1,000mm = 1,000,000 µm = 1,000,000,000nm 1mm = 1000 µm = 1000000nm 1 µm = 1000nm From the Virtual Microbiology Classroom on ScienceProfOnline.com Click link for an interactive “Size of Microscopic Things” animation on Cells Alive. These are prokaryote E. coli bacteria on the head of a steel pin. Most prokaryotes are beneficial; we couldn’t live without them. (e.g. Nitrogenfixing bacteria) Some cause illness bubonic plague, diphtheria, salmonella Approximately 5000 species have been identified. Archaea are thought to be more closely related to eukaryotes than to bacteria. Structure, function, and reproduction of prokaryotes II. A. Most prokaryotes are unicellular. B. Three (3) common shapes: cocci (round); bacilli (rod); helical (spiral) 3 Shapes of Bacteria Bacteria are classified by shape into 3 groups: Spiral: spirilla rod-shaped: bacilli, bacillus Round: Cocci Staph strep Do ALL Cells have a cell membrane? YES!!! HOW IS A CELL MEMBRANE DIFFERENT THAN A CELL WALL? 7 Major Structures of a Bacteria Cell •Capsule •Cell wall •Ribosomes •Nucleoid •Flagella •Pilli •Cytoplasm 7 Major Structures of a Bacteria Cell Cell wall Thick outer covering that maintains the overall shape of the bacterial cell 7 Major Structures of a Bacteria Cell Ribosomes cell part where proteins are made Ribosomes give the cytoplasm of bacteria a granular appearance in electron micrographs 7 Major Structures of a Bacteria Cell Nucleoid a ring made up of DNA 7 Major Structures of a Bacteria Cell Flagella a whip-like tail that some bacteria have for locomotion 7 Major Structures of a Bacteria Cell Pilli hollow hairlike structures made of protein allows bacteria to attach to other cells. Pilli-singular Pillus-plural 7 Major Structures of a Bacteria Cell Cytoplasm clear jellylike material that makes up most of the cell Reproduction of Bacteria •Binary Fission- the process of one organism dividing into two organisms •Fission is a type of asexual reproduction •Asexual reproduction- reproduction of a living thing from only one parent How?... The one main (circular) chromosome makes a copy of itself Then it divides into two BINARY FISSION Bacteria dividing Completed Prokaryote cells are simply built (example: E. coli) capsule: slimy outer coating cell wall: tougher middle layer cell membrane: delicate inner skin Prokaryote cells are simply built (example: E. coli) cytoplasm: inner liquid filling DNA in one big loop pilli: for sticking to things flagella: for swimming ribosomes: for building proteins Most prokaryotes secrete sticky substances that form a protective layer and enable them to adhere to substrates. a. The sticky protective layer secreted by prokaryotes is called the capsule. b.Some prokaryotes adhere to substrates using pili. c. Some pili are specialized for DNA transfer. This process is called conjugation; note for later in class. Organelles Cytoplasm Ribosomes Nuclear Zone DNA Plasmid Cell Membrane Mesosome Cell Wall Capsule (or slime layer) Flagellum Prokaryote Feeding Photosynthetic: energy from sunlight Disease-causing: feed on living things Decomposers: feed on dead things Chemotrophs – Use the carbon and other chemicals in environment to make food. Eukaryotic Cells Eukaryotic Cells -possess a membrane-bound nucleus -are more complex than prokaryotic cells -compartmentalize many cellular functions within organelles and the endomembrane system -possess a cytoskeleton for support and to maintain cellular structure 66 Eukaryotic Cells 67 Eukaryotic Cells 68 Eukaryotes are bigger and more complicated Have organelles Have chromosomes can be multicellular include animal and plant cells Organelles Cytoplasm Nucleus Mitochondria Chloroplast Ribosomes RER SER Golgi body Vacuoles Organelles Lysosomes Cytoskeleton Centriole Cilium and Flagellum Microvilli Cell membrane Cell Wall Kingdoms Plant Animal Fungi Protista Organelles are membrane-bound cell parts Mini “organs” that have unique structures and functions Located in cytoplasm How do animal cells move? Some can crawl with pseudopods Some can swim with a flagellum Some can swim very fast with cilia Pseudopods means “fake feet” extensions of cell membrane example: ameoba Flagellum/flagella large whiplike tail pushes or pulls cell through water can be single, or a pair Cilia fine, hairlike extensions attached to cell membrane beat in unison LifeStyles Join with alike cells to form tissues Tissues to form organs Organs to form organ systems Feeding Autotrophic Make own food - photosynthesis Heterotrophic Must obtain food Carnivore Herbivore Omnivore Detritivore Eukaryote cells can be multicellular The whole cell can be specialized for one job cells can work together as tissues Tissues can work together as organs Advantages of each kind of cell architecture Prokaryotes Eukaryotes simple and easy to grow can specialize fast reproduction multicellularity all the same can build large bodies Examples of specialized euk. cells liver cell: specialized to detoxify blood and store glucose as glycogen. sperm cell: specialized to deliver DNA to egg cell Mesophyll cell specialize d to capture as much light as possible inside a leaf Cell Structures Cell membrane delicate lipid and protein skin around cytoplasm found in all cells Nucleus a membrane-bound sac evolved to store the cell’s chromosomes(DNA ) has pores: holes Nucleolus inside nucleus location of ribosome factory made or RNA mitochondrion makes the cell’s energy the more energy the cell needs, the more mitochondria it has Ribosomes build proteins from amino acids in cytoplasm may be freefloating, or may be attached to ER made of RNA Endoplasmic reticulum may be smooth: builds lipids and carbohydrates may be rough: stores proteins made by attached ribosomes Golgi Complex takes in sacs of raw material from ER sends out sacs containing finished cell products Lysosomes sacs filled with digestive enzymes digest worn out cell parts digest food absorbed by cell Centrioles pair of bundled tubes organize cell division Cytoskeleton made of microtubules found throughout cytoplasm gives shape to cell & moves organelles around inside. Structures found in plant cells Cell wall very strong made of cellulose protects cell from rupturing glued to other cells next door Vacuole huge waterfilled sac keeps cell pressurized stores starch Chloroplasts filled with chlorophyll turn solar energy into food energy How are plant and animal cells different? Structure cell membrane nucleus nucleolus ribosomes ER Golgi centrioles cell wall mitochondria cholorplasts One big vacuole cytoskeleton Animal cells Yes Yes yes yes yes yes yes no yes no no yes Plant cells yes yes yes yes yes yes no yes yes yes yes Yes How did organelles evolve? many scientists theorize that eukaryotes evolved from prokaryote ancestors. in 1981, Lynn Margulis popularized the “endosymbiont theory.” Endosymbiont theory: a prokaryote ancestor “eats” a smaller prokaryote the smaller prokaryote evolves a way to avoid being digested, and lives inside its new “host” cell kind of like a pet. Endo = inside Symbiont = friend the small prokaryotes that can do photosynthesis evolve into chloroplasts, and “pay” their host with glucose. The smaller prokaryotes that can do aerobic respiration evolve into mitochondria, and convert the glucose into energy the cell can use. Both the host and the symbiont benefit from the relationship Chlorella are tiny green cells that live inside some amoeba... endosymbiosis may still be evolving today!